22,3,1000.000000000000 # the node 22 has a force of 1000 [N] in z direction.
23,3,500.000000000000 # the node 23 has a force of 500 [N] in z direction.
...

In order to include forces correctly in C3D10 element nodes, I need to define correctly the aforementioned 3 components.

1.- The definition of a manually selected nodes is not a handicap, it is discussed here: https://forum.freecadweb.org/viewtopic. ... 10#p258488
2.- The definition of the direction is not a handicap. x=1,y=2,z=33.- My problem is here in the third component: the magnitude of the force for each node.

The last part has a product of two variables: direction_vec.x * node_load direction_vec is not a handicap. The definition of Node_load is my real problem

In order to include forces correctly in C3D10 element nodes, I need to find in FreeCAD folder the python or C++ scripts where the following four functions are defined:

So, If I want to simulate an uniform pressure normal to all surfaces of a single tetrahedron (element C3D10), I need to:
1.- Find mid-side nodes of the element.
2.- Calculate the area of each surface of a tetrathedon.
3.- Calculate the direction of the vector for each force (normal to all surfaces).
4.- Apply the formula of the book to the mid-side nodes.

Finally, write everything in the .inp file. I am right?

Is it necessary to write the values of the nodes placed at the corner in the .inp file?

So, If I want to simulate an uniform pressure normal to all surfaces of a single tetrahedron (element C3D10), I need to:
1.- Find mid-side nodes of the element.
2.- Calculate the area of each surface of a tetrathedon.
3.- Calculate the direction of the vector for each force (normal to all surfaces).
4.- Apply the formula of the book to the mid-side nodes.

To be honest I'm not that deep at FEM in theory. I used the factors from the bood for a 2nd order element, as it is what CalculiX has. I developed the factors and made a test If you use the Calculix cantilever example from StartWB and load it with a tension force the front face keeps in direction of the beam. If you use different factors the face drifts to one side ... There are some topics on the forum in this regard which show some pics in this regard.

Would be great if someone with good FEM background knowledge could proof if we gone do the right thing.

So, If I want to simulate an uniform pressure normal to all surfaces of a single tetrahedron (element C3D10), I need to:
1.- Find mid-side nodes of the element.
2.- Calculate the area of each surface of a tetrathedon.
3.- Calculate the direction of the vector for each force (normal to all surfaces).
4.- Apply the formula of the book to the mid-side nodes.